Reduction of power consumption and time for time-of-flight positioning via neighbor list

ABSTRACT

Systems and methods are directed to use of a neighbor list for wireless indoor navigation. The neighbor list may include related information regarding all neighboring access points (APs). The neighbor list can be transmitted, at least partially, to include the related information of a desired number of or all APs in the neighbor list from one AP to a wireless device. The neighbor list can be transmitted in a Neighbor Report Response (NRR) or a time-of-flight (ToF) Response and allow the wireless device to scan for minimal number of APs for ToF measurements. By using the neighbor list, power consumption and time can be significantly reduced during wireless indoor navigation.

TECHNICAL FIELD

This disclosure relates generally to the field of wirelesscommunications, and in particular, to wireless indoor navigation systemsand methods.

BACKGROUND ART

Outdoor navigation has been widely deployed, given the development ofvarious global-navigation-satellite-systems (GNSS). However, suchnavigation systems do not work well for indoor applications, as indoorenvironments do not facilitate the effective reception of signals fromGNSS satellites.

Indoor navigation systems have been recently developed that are based onwireless networks, such as, for example, Wi-Fi. However, such networksare specifically designed and used for wireless communications and notnecessarily optimized for navigation or positioning. Indeed, variousattempts have been made to develop indoor navigation systems usingtime-of-flight (ToF) methods. Time-of-flight (ToF) is basically theoverall time that a signal propagates from a wireless device to anetwork access point (AP) and back to the wireless device. This timevalue can be converted into distance using the speed of light. ToFmethods are considered robust and scalable, but require hardware changesto WiFi modem. ToF methods also generally pose a high barrier-to-entry,since implementation requires substantive changes in current navigationand wireless technologies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a functional block diagram of a wireless locationidentification system, in accordance with various aspects and principlesof the present disclosure.

FIG. 2 depicts a flow diagram illustrating an exemplary method forwireless location identification, in accordance with various aspects andprinciples of the present disclosure.

FIG. 3 depicts a flow diagram illustrating another exemplary method forwireless location identification, in accordance with various aspects andprinciples of the present disclosure.

DETAILED DESCRIPTION

In the description that follows, like components have been given thesame reference numerals, regardless of whether they are shown indifferent embodiments. To illustrate an embodiment(s) of the presentdisclosure in a clear and concise manner, the drawings may notnecessarily be to scale and certain features may be shown in somewhatschematic form. Features that are described and/or illustrated withrespect to one embodiment may be used in the same way or in a similarway in one or more other embodiments and/or in combination with orinstead of the features of the other embodiments.

In accordance with various embodiments of this disclosure, what isproposed is systems and methods for wireless indoor navigation by usinga neighbor list. The neighbor list may include related informationregarding all neighboring access points (APs). The neighbor list can betransmitted, at least partially, to include the related information of adesired number of or all APs in the neighbor list from one AP to awireless device.

For example, in one embodiment, a system is presented that includes awireless device, and a plurality of access points (APs). The wirelessdevice can be configured to receive at least a neighbor list from one APof the plurality of APs. The neighbor list from the one AP may includeinformation regarding the plurality of APs.

In another embodiment, a method is presented by using a wireless deviceto scan a plurality of access points (APs) to use one AP from theplurality of APs. The wireless device may request a Neighbor Report fromthe one AP and then receive a Neighbor Report Response (NRR) from theone AP in response to the neighbor report request. The NRR received fromthe one AP can include a neighbor list including information regardingthe plurality of APs. A number of APs may then be chosen from theplurality of APs in the neighbor list by the wireless device. Todetermine a location of the wireless device, the wireless device maysend a time-of-flight (ToF) request to the number of APs for a ToFmeasurement.

In yet another embodiment, a method is presented by using a wirelessdevice to scan a plurality of access points (APs) to use one AP from theplurality of APs. The wireless device may send a time-of-flight (ToF)request to the one AP and then receive a ToF Response from the one AP inresponse to the ToF request. The ToF Response may include a neighborlist having information regarding the plurality of APs. A number of APsmay then be chosen from the plurality of APs in the neighbor list by thewireless device. To determine a location of the wireless device, thewireless device may send a time-of-flight (ToF) request to the number ofAPs for a ToF measurement.

These and other features and characteristics, as well as the methods ofoperation and functions of the related elements of structure and thecombination of parts and economies of manufacture, will become moreapparent upon consideration of the following description and theappended claims with reference to the accompanying drawings, all ofwhich form a part of this specification, wherein like reference numeralsdesignate corresponding parts in the various figures. It is to beexpressly understood, however, that the drawings are for the purpose ofillustration and description only and are not intended as a definitionof the limits of claims. As used in the specification and in the claims,the singular form of “a”, “an”, and “the” include plural referentsunless the context clearly dictates otherwise.

For conventional indoor navigation systems, the inventors have observedthat a wireless device desirous of achieving ToF-positioning has tofirst perform a passive scan at various frequency bands to identify allneighboring APs having ToF capabilities. Then, the wireless device hasto decide which APs it would like to send a ToF request to. This isachieved based on information that is transmitted from each of theneighboring APs to the wireless device. In so doing, a substantialamount of power is consumed and a significant amount of time is spent inthe preliminary stages of the indoor navigation process.

With this said, FIG. 1 depicts a functional block diagram of a wirelesslocation identification system 100 configured, for example, to performToF measurements, in accordance with various aspects and principles ofthe present disclosure. As shown in FIG. 1, system 100 includes multiplenetwork APs, e.g., AP1, AP2, AP3, AP4, etc., and wireless device 102 atan unknown position. Note that although FIG. 1 depicts four APs in thesystem, one of ordinary skill in the art would appreciate that thesystem 100 may include more or less than four APs. In one embodiment,system 100 incorporates at least three APs that may receive wirelesssignals from a wireless device that is at an unknown location.

It will be appreciated that, as used herein, the term “access point” or“AP” refers to any device with the ability to receive wireless signalsfrom one or more devices and provides access to a network, such as alocal area network (LAN) or the Internet, for example. An AP may beinstalled at a fixed terrestrial location or may be installed on avehicle or mobile apparatus. In one aspect, an AP may include afemtocell utilized to extend cellular telephone service into a businessor home. In such an implementation, one or more wireless devices maycommunicate with the femtocell via a code division multiple access(CDMA) cellular communication protocol, for example, and the femtocellwould provide the wireless devices access to a larger cellulartelecommunication network by way of another broadband network such asthe Internet. In certain aspects, an AP may be a dedicated ToF tag AP.The dedicated ToF tag AP may not be connected to a network but may haveToF capabilities to receive and respond to a ToF request, for example.Of course, these are example implementations utilizing one or morewireless devices and an AP, and the scope of claimed subject matter isnot limited in this respect.

Moreover, as used herein, the term “wireless device(s)” refers to anydevice that may communicate with other devices via wireless signals.Such devices may comprise, for example, a laptop, mobile device,cellular/smartphone, gaming device, tablet computer, a wireless-enabledpatient monitoring device, personal communication system (PCS) device,personal digital assistant (PDA), personal audio device (PAD), portablenavigational device, and/or any other electronic wireless-enabled deviceconfigured to receive a wireless signal. It may also include relativelystationary devices such as desktop computers with wireless capabilities.Such wireless devices may communicate via any number of wirelesscommunication protocols, examples of which are described below. Asdisclosed herein, the term wireless device may be interchangeably usedwith wireless user (or WiFi user), wireless STA (or WiFi STA), etc.

Further, as used herein, the term “network” refers to a wirelesscommunication network that may be utilized in example implementations asdiscussed below. The network may be configured to operate under avariety of wireless communication protocols and standards, such as, forexample, Wi-Fi, WiMax, WWAN, WLAN, WPAN, Bluetooth, GSM, CDMA, GPRS, 3Gor 4G, LTE, Wireless USB, the IEEE 802.11x standard, such as IEEE std.802.11k-2008 published Jun. 12, 2008, or IEEE std. 802.11-2012 publishedMar. 29, 2012, or any other implementation of a suitable wirelessstandard. It will be appreciated that the wireless communication is notlimited to any specific standard and the examples discussed may beimplemented separately or in combination with each other.

Returning to FIG. 1, in system 100, APs 1-4 may be devices that allowfor wireless devices to communicate with each other by acting as both atransmitter and receiver of WLAN radio signals. As noted above, APs 1-4may take the form of any APs as disclosed herein including, for example,dedicated hardware devices that include a built-in network adapter,antenna, radio transmitter, etc., while wireless device 102 may take theform, such as, for example, wireless telephone, notebook computer,personal digital assistant, etc.

System 100 employs a neighbor list mechanism 110 that is configured tocontain relevant information regarding neighboring APs. In this manner,by reaching one AP, instead of reaching each and every neighboring APs,relevant information regarding all neighboring APs can be transmittedfrom the one AP to wireless device 102. The neighbor list mechanism 110enables wireless device 102 to scan for a number of APs, e.g., having aminimal number of APs that is sufficient for the ToF measurements. Inother words, wireless device 102 does not need to scan all frequencybands, rather it will decide a minimal number of APs that wirelessdevice 102 wants to use for ToF by examining the neighbor list mechanism110 received from one AP used from all neighboring APs.

In some embodiments, neighbor list mechanism 110 may be incorporated ina Neighbor Report Response (NRR), according to IEEE 802.11x standard.The NRR is furnished by an AP in response to a Neighbor Report Requestinitiated by wireless device 102. It will be appreciated that the IEEE802.11x standard allows an AP to store a neighbor table. However,different from the standard neighbor table, by virtue of incorporatingneighbor list mechanism 110, the table is supplemented with relevantinformation about all neighboring APs.

In addition, the IEEE 802.11x standard enables wireless device 102 torequest a Neighbor Report from one AP. In accordance with variousembodiments, information of all neighboring APs may then be included inthe NRR in response to a Neighbor Report Request of wireless device 102from one AP. Because the NRR includes information of all neighboringAPs, by reaching this one AP, information of all neighboring APs can betransmitted from the single AP to wireless device 102.

As such, neighbor list mechanism 110 may comprise information elements(IEs) added to a NRR, or added into Neighbor Report Elements (e.g., assub-elements) of the NRR, or added into the basic service setidentification (BSSID) information fields of the Neighbor ReportElements of the NRR.

In other embodiments, neighbor list mechanism 110 may be piggybackedonto or otherwise coupled to an AP ToF response in reply to a ToFrequest by wireless device 102. The piggybacked neighbor list mechanism110 may, for example, comprise information elements (IEs) to includeinformation of all APs, or may be defined as sub-elements of NeighborReport Elements for all APs, or can be defined in the BSSID informationfield of Neighbor Report Elements, although the Neighbor Report Elementsare not contained in a NRR in this example.

In certain embodiments, information regarding all APs in neighbor listmechanism 110 may include any desired information of each AP accordingto applications and requirements of the indoor navigation system. In oneaspect, the information for each AP in neighbor list mechanism 110 mayinclude positioning information desired for indoor positioning ofwireless device 102 in a wireless communication system.

Table 1 depicts examples of positioning information of each AP of theneighboring APs in neighbor list mechanism 110. The positioninginformation may include information regarding, for example, (1) APposition indicative of geographic location of the AP; (2) AP positionaccuracy indicative of how accurate the obtained geographic location is;(3) AP position source indicative of which type of source the AP obtainsits geographic location; (4) time passed since AP position updateindicative of the last time the geographic location was updated; (5) APtiming offset calibration accuracy (e.g., which can be set to zero whenthe AP is not calibrated); (6) AP type; (7) distance from one or moreneighboring APs; etc.

TABLE 1 Positioning Information 1 AP position 2 AP position accuracy 3AP position source 4 Time passed since AP position update 5 AP timingoffset calibration 6 AP type 7 Distance from one or more neighboring APs. . . . . .

In turn, information regarding the AP type may include information ofwhether the AP is stationary or mobile, whether the AP is a pseudo AP ornot, whether the AP is a dedicated time-of-flight (ToF) tag AP or not,and/or whether the AP is a wireless AP or wireless non-AP (e.g., aclient). Moreover, information regarding distance from one or moreneighboring APs may include information of how far the AP is from otherneighboring APs.

In various embodiments, the AP position source can be manuallyconfigured, automatically deduced from other APs within certainaccuracy, provided by a networked server, etc. In certain embodiments,the pseudo-AP may be configured to provide lower radiated RF power,smaller coverage, and deployed for only location determination purposes.

As known in the art, the standard Neighbor Report Response (NRR) uses anAction frame body format. The format of the Action field in the NRR isshown in FIG. 8-443, IEEE 802.11-2012, section 8.5.7.7, for example, andindicated below.

FIG. 8-443 NRR frame Action field format at IEEE 802.11-2012 CategoryRadio Measurement Dialog token Neighbor Report action Elements

In certain embodiments, neighbor list mechanism 110 includes informationof all neighboring APs that may be defined in an NRR as informationelements (IEs), e.g., see Table 2a. The defined information elements caninclude, for example, positioning information (see Table 1) of allneighboring APs, and can be included into the standard NRR frame.

TABLE 2a NRR frame Action Field Format Category Radio Dialog NeighborInformation Measurement token Report Elements action Elements of all APs

In other embodiments, neighbor list mechanism 110 includes informationof all neighboring APs that may be added into Neighbor Report Elements,e.g., see FIG. 8-215 of section 8.4.2.39 of 802.11-2012, of standardNRR.

FIG. 8-215 Neighbor Report Element format at IEEE 802.11-2012 ElementLength BSSID BSSID Oper- Channel PHY Optional ID Infor- ating NumberType Sub- mation Class elements

For example, relevant information of each AP (e.g., see Table 1) may beadded into each Neighbor Report Element of standard NRR frame, forexample, as a sub-element as depicted in Table 2b. In other embodiments,information of each AP (e.g., positioning information in Table 1) may beadded into the BSSID information field of each Neighbor Report Element,as depicted in Table 2c. In yet other embodiments, some of informationof each AP can be added into a sub-element, and some of information ofeach AP may be added into the BSSID information field of the eachNeighbor Report Element.

TABLE 2b Neighbor Report Element format Element Length BSSID BSSIDOperating Channel PHY Optional Subelement ID Information Class NumberType Subelements of each AP

TABLE 2c Neighbor Report Element format Element Length BSSID BSSID Oper-Channel PHY Optional ID Infor- ating Number Type Sub- mation Classelements Infor- mation of each AP

By using Neighbor Report Element format, as depicted in Table 2b and/orTable 2c, relevant information of all neighboring APs as desired can beinclude in the Neighbor Report Elements of the NRR to provide neighborlist mechanism 110.

In embodiments without being configured in an NRR, neighbor listmechanism 110 may be transmitted from one AP to wireless device 102 inany suitable manner. For example, neighbor list mechanism 110 may bepiggybacked onto a ToF response and defined as information elements assimilarly shown in Table 2a, or as Neighbor Report Elements with eachNeighbor Report Element having a format as similarly shown in Tables 2band/or 2c.

FIG. 2 depicts a flow diagram illustrating an exemplary method 200,e.g., including ToF measurements using similar or same system asdepicted in FIG. 1, in accordance with various aspects and principles ofthe present disclosure. As shown in FIG. 2, method 200 may use a systemor network having a plurality of APs, e.g., AP1, AP2, AP3, until APN(where N is 4 or greater in this case), and a wireless device 202 at anunknown position.

At interval 210 of FIG. 2, RF beacon signal may be broadcasted,transmitted from each of all neighboring APs. As the wireless device 202scans the entire frequency range, it may use the first AP that itencounters. In certain embodiments, the wireless device 202 may use oneAP of all neighboring APs, e.g., according to a distance (e.g., thenearest) from the wireless device 202, or according to other operationalcriteria.

At interval 220 of FIG. 2, the wireless device 202 may send an actionframe to request a Neighbor Report from the one AP as used in theinterval 210. In some embodiments, this Neighbor Report Request may needto be enhanced so that the wireless device 202 is able to indicate thatit is interested in receiving the neighboring list containinginformation (e.g., the positioning information in Table 1) of allneighboring APs. For example, standard Neighbor Report Request (see FIG.8-442 in section 8.5.7.6 at 802.11-2012) can be enhanced via an optionalsub-element or an added sub-element to indicate that the wireless deviceis interested in receiving the neighbor list.

At interval 230 of FIG. 2, in response to the Neighbor Report Request, aNRR containing at least the neighbor list can be sent from the one AP tothe wireless device 202. Based on the information of all APs obtained inthe NRR from the one AP, wireless device 202 may choose a number of APs,e.g., a minimal number such as one or more of APs, with all theinformation needed to conduct reliable ToF measurements. For example,when trilateration or other similar positioning techniques are used forToF measurements, at least three APs may be chosen and used at interval230. In another example, when sensors or other similar positioningdevices/techniques are used for ToF measurements, one or two (or three,etc.) APs may be chosen and used in the ToF measurements.

At interval 240 of FIG. 2, wireless device 202 may then request ToF fromeach of the number of APs, e.g., APs 1, 3, 5, 6, and 8 as shown in FIG.2, chosen at interval 230.

At interval 250 of FIG. 2, in response to the ToF request, ToF responsemay be transmitted from each of the number of APs. The distance betweenthe wireless device 202 and each AP involved can be calculated and aposition of the wireless device 202 may then be estimated according tothe ToF measurements, e.g., via trilateration techniques.

In this manner, having relevant information, such as,positioning-related data, of all neighboring APs in neighbor listmechanism 110, as embodied in an NRR frame by the various techniquesdisclosed herein, enables wireless device 102 to interact with one AP toreceive all the information in neighbor list mechanism 110, from which aminimal number of APs can be determined to conduct ToF measurements.

Alternatively, neighbor list mechanism 110 may not be contained in aNRR, and may be transmitted from one AP to wireless device 102, e.g., asa piggybacked information. That is, neighbor list mechanism 110 can bepiggybacked onto or otherwise coupled to a ToF response in response to aToF request by wireless device 102 from an AP, although neighbor listmechanism 110 may still be similarly defined as information elements(IEs) to include information of all APs, or defined in sub-elements ofNeighbor Report Elements for all APs, or defined in the BSSIDinformation fields of the Neighbor Report Elements.

To this end, FIG. 3 depicts a flow diagram illustrating anotherexemplary method 300, e.g., including ToF measurements using similar orsame system as depicted in FIGS. 1-2, in accordance with various aspectsand principles of the present disclosure. As shown in FIG. 3, method 300may use a system or network having a plurality of APs, e.g., AP1, AP2,AP3, until APN (where N is 4 or greater in this case), and a wirelessdevice 302 at an unknown position.

At interval 310 of FIG. 3, RF beacon signal can be broadcast,transmitted from each of all neighboring APs. As the wireless device 302scans the entire frequency range, it may use the first AP that itencounters, or in certain embodiments, it may use the one AP accordingto, e.g., a distance (e.g., the nearest) from the wireless device 202,or according to other operational criteria.

At interval 320 of FIG. 3, the wireless device 302 can then request ToFfrom the one AP as used at interval 310.

At interval 330 of FIG. 3, in reply to the ToF Request, a ToF Responseat least containing the above mentioned neighbor list including relatedinformation of all APs can be sent from the one AP to the wirelessdevice 302, e.g., in an unassociated state. In some embodiments, the oneAP may transmit the entire neighbor list containing all neighboring APsto the wireless device. In other embodiments, the one AP may transmit apart of the entire neighbor list containing a certain number ofneighboring APs as desired. Based on the related information of all APsobtained in the Neighbor list of the one AP, wireless device 302 canchoose a number of APs, e.g., a minimal number of APs with all theinformation needed for the ToF measurements. The minimal number of APsmay refer to a number of one or more APs depending on the positioningdevice/techniques used for the ToF measurements as described herein.

At interval 340 of FIG. 3, wireless device 302 can then request ToF fromeach of the number of APs, e.g., APs 3, 5, 6, and 8 as shown in FIG. 3,as chosen at interval 330.

At interval 350 of FIG. 3, in reply to the ToF request, ToF response canbe transmitted from each of the number of APs. The distance betweenwireless device 302 and each of the number of APs can be calculated anda position of wireless device 302 can then be estimated according to theToF measurements, e.g., via trilateration techniques.

In this manner, each AP in a system for positioning wireless device 102may provide relevant information (e.g., positioning information) of allneighboring APs in neighbor list mechanism 110. The information of allneighboring APs can be added into a Neighbor Report Response or can bepiggybacked onto a ToF response, in response to a respective request bythe wireless device from one AP. Based on neighbor list mechanism 110obtained from the one AP (instead of all APs), minimal number of APs canbe chosen to request ToF therefrom to position wireless device 102.Accordingly, power consumption and time can be significantly reduced.

Having thus described the basic concepts, it will be rather apparent tothose skilled in the art after reading this detailed disclosure that theforegoing detailed disclosure is intended to be presented by way ofexample only and is not limiting. Various alterations, improvements, andmodifications will occur and are intended to those skilled in the art,though not expressly stated herein. These alterations, improvements, andmodifications are intended to be suggested by this disclosure, and arewithin the spirit and scope of the exemplary embodiments of thisdisclosure.

Moreover, certain terminology has been used to describe embodiments ofthe present disclosure. For example, the terms “one embodiment,” “anembodiment,” and/or “some embodiments” mean that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Therefore, it is emphasized and should be appreciated that two or morereferences to “an embodiment” or “one embodiment” or “an alternativeembodiment” in various portions of this specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures or characteristics may be combined assuitable in one or more embodiments of the present disclosure. Inaddition, the term “logic” is representative of hardware, firmware,software (or any combination thereof) to perform one or more functions.For instance, examples of “hardware” include, but are not limited to, anintegrated circuit, a finite state machine, or even combinatorial logic.The integrated circuit may take the form of a processor such as amicroprocessor, an application specific integrated circuit, a digitalsignal processor, a micro-controller, or the like.

Furthermore, the recited order of processing elements or sequences, orthe use of numbers, letters, or other designations therefore, is notintended to limit the claimed processes and methods to any order exceptas can be specified in the claims. Although the above disclosurediscusses through various examples what is currently considered to be avariety of useful embodiments of the disclosure, it is to be understoodthat such detail is solely for that purpose, and that the appendedclaims are not limited to the disclosed embodiments, but, on thecontrary, are intended to cover modifications and equivalentarrangements that are within the spirit and scope of the disclosedembodiments.

Similarly, it should be appreciated that in the foregoing description ofembodiments of the present disclosure, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure aiding in theunderstanding of one or more of the various inventive embodiments. Thismethod of disclosure, however, is not to be interpreted as reflecting anintention that the claimed subject matter requires more features thanare expressly recited in each claim. Rather, as the following claimsreflect, inventive embodiments lie in less than all features of a singleforegoing disclosed embodiment. Thus, the claims following the detaileddescription are hereby expressly incorporated into this detaileddescription.

What is claimed is:
 1. An apparatus comprising an integrated circuit tobe used in a wireless station (STA), the integrated circuit to cause thewireless station to: send a time-of-flight (ToF) measurement request toan access point (AP); receive a message from the AP, the messagecomprises a neighbor report element comprising a neighbor list; performToF measurements with two or more APs from the neighbor list; anddetermine a location of the wireless station based on the ToFmeasurements with at least some of the two or more APs.
 2. The apparatusof claim 1, wherein the neighbor report element comprises: an element IDfield, a length field, a Basic Service Set Identifier (BSSID) field, aBSSID information field, an operating class field, a channel numberfield, and a physical layer (PHY) type field.
 3. The apparatus of claim2, wherein the BSSID information field comprises an indication of ToFcapabilities of an AP of said neighbor list.
 4. The apparatus of claim 1comprising a transmitter and a receiver.
 5. An apparatus comprising anintegrated circuit to be used with an access point (AP), the integratedcircuit is to cause the AP to: receive a time-of-flight (ToF)measurement request from a wireless station (STA); send a message to theSTA, the message comprises a neighbor report element comprising aneighbor list; and perform ToF range measurements with the STA, the ToFmeasurements configured to be used to calculate a distance to the STA.6. The apparatus of claim 5, wherein the neighbor report elementcomprises: an element ID field, a length field, a Basic Service SetIdentifier (BSSID) field, a BSSID information field, an operating classfield, a channel number field, and a physical layer (PHY) type field. 7.The apparatus of claim 6, wherein the BSSID information field comprisesan indication of ToF capabilities of an AP of said neighbor list.
 8. Theapparatus of claim 5 comprising: a radio transmitter; and a networkadaptor.
 9. The apparatus of claim 5 comprising an antenna.
 10. Anon-transitory computer-readable storage medium that stores instructionsfor execution by an integrated circuit of a wireless station to performoperations to cause the wireless station to: send a time-of-flight (ToF)measurement request to an access point (AP); receive a message from theAP, the message comprises a neighbor report element comprising aneighbor list; perform ToF measurements with two or more APs from theneighbor list; and determine a location of the wireless station based onthe ToF measurements with at least some of the two or more APs.
 11. Thenon-transitory computer-readable storage medium of claim 10, wherein theneighbor report element comprises: an element ID field, a length field,a Basic Service Set Identifier (BSSID) field, a BSSID information field,an operating class field, a channel number field, and a physical layer(PHY) type field.
 12. The non-transitory computer-readable storagemedium of claim 11, wherein the BSSID information field comprises anindication of ToF capabilities of an AP of said neighbor list.
 13. Anon-transitory computer-readable storage medium that stores instructionsfor execution by an integrated circuit of an access point (AP) toperform operations to cause the AP to: receive a time-of-flight (ToF)measurement request from a wireless station (STA); send a message to theSTA, the message comprises a neighbor report element comprising aneighbor list; and perform ToF measurements with the STA, the ToFmeasurements configured to be used to calculate a distance to the STA.14. The non-transitory computer-readable storage medium of claim 13,wherein the neighbor report element comprises: an element ID field, alength field, a Basic Service Set Identifier (BSSID) field, a BSSIDinformation field, an operating class field, a channel number field, anda physical layer (PHY) type field.
 15. The non-transitorycomputer-readable storage medium of claim 14, wherein the BSSIDinformation field comprises an indication of ToF capabilities of an APof said neighbor list.